At one point in the season opener against Buffalo, safety Christian Bryant was the only returning defensive starter for Ohio State on the field.

If the Buckeyes could only have one, Bryant was a good one to have. He was a playmaker. Perhaps more important, he was a vocal leader.

Now the Buckeyes will have to move on to play their highest-ranked opponent of the season without him. Bryant suffered a broken left ankle at the end of the Wisconsin game on Saturday night. He had surgery on Sunday morning. His father, Ronnie, said that doctors have estimated recovery time at three months.

“How much Christian gives to the program, it’s really hard to equal,” defensive tackle Michael Bennett said. “I wish you guys could hear some of the speeches he gives us in the locker room. He’s a huge leader on the field and a huge leader off the field. It’s a hard loss. But it’s Ohio State. We have guys who’ll step up and fill that role.”

The top contenders to take Bryant’s spot are fifth-year senior Corey Brown, redshirt freshman Tyvis Powell and true freshman Vonn Bell. Powell has been a quasi-starter as the slot cornerback in the nickel formation, which has essentially been the Buckeyes’ base defense this season.

“You can’t replace him,” defensive coordinator Luke Fickell said on Saturday night of Bryant. “I’m not going to sit here and tell you we’re going to have someone go in there who’s going to be the same heart and soul and be the leader we’ve had with Christian.

“But maybe that means someone can be a bigger leader. Curtis Grant will have to be a bigger leader. And Doran Grant’s got to be a bigger leader.”

Cornerbacks coach Kerry Coombs said he expects Brown to get first dibs at filling Bryant’s position in practice because of his experience.

Coach Urban Meyer said the defensive coaches met at 7 a.m. yesterday to discuss the situation. He said that a year ago, he would have taken the lead in making the decision. But as he has grown comfortable with his defensive coaching staff, Meyer said he will put more stock in their opinions.

It’s not ideal that Northwestern (4-0) is the next opponent.

“This is a very complicated offense,” Meyer said. “One of the disappointing things we had last Saturday was not just a couple guys got beat, but we had some errors in checks and communication. We can’t have that. So that’s where maybe (Brown) has more of an advantage over a Vonn Bell or a Tyvis Powell.”

Ohio State was burned for a career-high 295 passing yards by Wisconsin sophomore Joel Stave. Although the Buckeyes’ pass defense was hardly stellar, coaches said that they were willing to risk yards through the air by concentrating on containing the Badgers’ run game, which is their forte. Wisconsin gained only 104 yards on the ground.

Northwestern will require a different defensive game plan. The Wildcats, coming off a bye week, expect to have standout running back Venric Mark back from a leg injury. But they don’t rely on the run the way Wisconsin does.

For the Wildcats, once a league laughingstock but now trying to establish themselves as a perennial Big Ten contender, this is being viewed as the biggest game at Ryan Field in recent memory. ESPN GameDay will originate from Evanston, Ill., for the first time since 1995.

“Another night game, GameDay and it will be a heck of an atmosphere,” Meyer said. “So we look forward to the challenge.”